Semi-automated plantar surface sensation detection device

ABSTRACT

Disclosed herein is a device for repeatably and accurately measuring the threshold sensitivity of the skin on a body part or surface such as the plantar surface of the foot. The machine uses a monofilament pressure test, where a monofilament is applied to the surface of the skin until it buckles at a corresponding force. The device may measure a broad range of pressures and responsive sensation in the patient using multiple applications of the monofilament. The patient indicates a positive or negative response, based on whether the patient sensed the monofilament pressure. The machine may include a foot clamping assembly, a support chassis, a linear motion translation assembly for locating the monofilament at a given position for testing, and a camera for taking images used to identify testing locations and report results. Methods of use and testing protocols are also described herein.

CROSS-REFERENCE TO OTHER APPLICATIONS

This application claims the benefit of filing of U.S. patent applicationSer. No. 17/027,464 filed on Sep. 21, 2020, and on U.S. ProvisionalPatent Application No. 62/903,211, filed on Sep. 20, 2019. U.S.Provisional Patent Application No. 62/903,211 is incorporated byreference herein.

BACKGROUND OF THE ART

Diabetes is an ever-increasing diagnosis that carries with it numerousneuropathic complications. It is estimated that over 7.5% of adults inthe United States have diabetes; this number reaches as high as 30million Americans with the inclusion of children. It was reported thatin 2019, 463 million adults have been reported to suffer from diabetesand it is protected to reach 700 million by 2045.

The cost of care of diabetes is fast approaching $300 billion per yearwith at least 60% of this cost directed toward hospitalizations andtreatment of complications. Neuropathy, sometimes referred to as“diabetic foot”, complications are the most common and lead toulcerations and amputation. The cost of diabetic foot disease isestimated at over $10 billion per year, above the cost of routinediabetic care. Eighty-five percent of all amputations are attributed topreceding foot ulcerations. Some individuals with severe neuropathy maystep on a nail and not even feel it. Such injuries, and other lesssevere injuries, can lead to infections, ulceration, and amputations. Aninfection or ulceration may start off with just one small part of thefoot, but left untended, amputation may be necessary for the entire footor even of a limb. In fact, a lower limb amputation occurs on averageevery 30 seconds as a result of neuropathy. Burning feet is one of themost common symptoms found in those who suffer from neuropathy, inaddition to shooting pain, an electrical sensation, numbness, and lossof sensation. Ultimately 40 to 60 million people suffer from neuropathycomplications.

The standard for evaluation of diabetic feet has traditionally included:foot inspection, checking for peripheral pulses, the ability to detectvibration and ankle reflex, the sensing of pinprick, the ability todistinguish between hot and cold, and the monofilament test. Amongthese, the monofilament test is most often relied upon and has beenoccasionally referred to as the “gold standard” of neuropathyassessment. In the monofilament test, monofilaments, made of a singlefiber of nylon, and are calibrated to reproduce a consistent bucklingstress. Monofilaments (commonly known as Semmes-Weinstein monofilaments)are a popular choice for neuropathy assessment because they arenoninvasive, easy to use, quick, and are relatively cheap when comparedto other testing methods. The monofilament is applied by handperpendicular to the skin until it bends or buckles. As the monofilamentis inserted the amount of force it produces increases until it buckles.Monofilaments can be sized to apply a desired buckling force, typicallymeasured in grams of force (1 gram of force (1 gF)=9.068 mN).Monofilaments can range from 0.008 to 300 gF, however they are typicallyexpressed using an evaluator size. This buckling force is correlated toan evaluator size, or monofilament gauge, which is a logarithmicrelationship between the force applied in gF. For example, the 10-gFmonofilament is designated as a 5.07 evaluator. There are 5classifications of plantar foot surface threshold sensitivity: normal(0.008-0.4 gF), diminished light touch (0.6-2.0 gF), diminishedprotective sensation (4.0-8.0 gF), loss of protective sensation (10-180gF), and deep pressure sensation only (300 gF). The 10-gF monofilamentis used most extensively to measure an individual's threshold ofsensation, as it this value marks the beginning of the loss ofprotective sensation in individuals. When the monofilament has beenproperly calibrated it can apply a repeatable force consistently. The10-gF monofilament has been found to produce repeatable and accurateresults.

Despite the extensive use of the monofilament test, it has severaldrawbacks. A physician may apply the monofilament at too high a speed,thereby applying a greater force than the monofilament is rated for.Additionally, the monofilament may be inserted at an angle. Furthermore,an individual doctor applying the monofilament may not consider thetopography of the skin, such as smoothness versus roughness and fattyversus boney surfaces. In addition, monofilaments may differ in lengthor diameter, or be bent or curved out of the box. Finally, differentlocations of the foot may be tested at different screenings over time.For all of these reasons, it is impossible to achieve accurate,repeatable measurements that may be tracked over time.

What is needed, then, is a device that can repeatably conduct themonofilament test. Such a machine may also optionally overcome otherdisadvantages of monofilament testing using hand-applied monofilaments.

SUMMARY OF THE INVENTION

In some respects the invention is directed to a machine for evaluatingthe presence of neuropathy in a patient, having a testing plate having afirst side and a second side and comprising a plurality of holes; aclamp operable to secure the tested area of the patient's skin to thefirst side of the testing plate; a camera operable to take a photographof the patient's skin visible through the holes from the second side ofthe testing plate; a head assembly translatable in an X/Y plane parallelto the second side of the testing plate and comprising a retractablemonofilament; and a computer programmed to receive input for selecting atesting location on the patient's skin wherein the testing location iscorrelated with one of the plurality of holes in the testing plate,position the head assembly over the testing location, and apply themonofilament to the patient's skin at the testing location and at aspecified force.

In other respects the invention is directed to a machine for evaluatingthe presence of neuropathy in a patient, having a testing plate having afirst side and a second side and comprising a plurality of holes; meansfor securing a tested body part of the patient to the first side of thetesting plate; means for visually identifying multiple testing locationscorrelated to a region of the patient's skin visible through the holesfrom the second side of the testing plate; means for selecting aspecified testing location; means for directing a monofilament to besituated over the specified testing location; and means for driving themonofilament against the patient's skin at the specified testinglocation with a specified force.

In other respects the invention is directed to a method for evaluatingthe presence of neuropathy in a patient, having the steps of securing atested body part of the patient to a first side of a testing plate, thetesting plate comprising a plurality of holes; taking an image of thetested body part of the patient as viewed from a second side of atesting plate through the plurality of holes; selecting a first testinglocation, the first testing location correlated to a first region of thetested body part visible through the plurality of holes; directing amonofilament over the first testing location; and driving themonofilament against the patient's skin at the first testing locationwith a first specified force.

Other aspects of the invention are described further with respect to thedetailed description and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an embodiment of the neuropathy assessment machine shown inan upright, perspective view.

FIG. 2 shows a camera assembly according to an embodiment of theinvention.

FIG. 3 shows the camera assembly of FIG. 2 in further detail, accordingto an embodiment of the invention.

FIG. 4 shows an isolated view of the foot clamping apparatus accordingto an embodiment of the invention.

FIG. 5 shows an isolated view of the linear translation assemblyaccording to an embodiment of the invention.

FIG. 6 shows another view of the linear translation assembly accordingto an embodiment of the invention.

FIG. 7 shows a view of the head assembly according to an embodiment ofthe invention.

FIGS. 8A and 8B show additional views of the head assembly according toan embodiment of the invention.

FIG. 9A shows a front profile view of the machine according to anembodiment of the invention.

FIG. 9B shows a section view of the machine taken along line A-A in FIG.9A.

FIG. 10 shows a plan view detail of head assembly and the foot plateaccording to an embodiment of the invention.

FIG. 11 shows an electronic counter device according to an embodiment ofthe invention.

FIG. 12A shows a plan view of a counter device according to anembodiment of the invention.

FIG. 12B shows a section view of the counter device along the sectionline C-C shown in FIG. 12A.

FIG. 13 shows a wiring diagram of the electronic components according toan embodiment of the invention.

FIG. 14 shows an exemplary image of a foot for testing as taken by thecamera according to an embodiment of the invention.

FIG. 15 shows a sensitivity map according to an embodiment of theinvention.

FIG. 16 shows a testing flowchart according to an embodiment of theinvention.

DETAILED DESCRIPTION Introductory Information and Definitions

Disclosed herein is a device for measuring the threshold point touchsensitivity of individuals. Single or multiple discrete amounts ofnoninvasive pressures may be applied at one or multiple locations uponthe skin surface of a body part. Locations may be selected for pressureevaluation from an image of the plantar surface against the plate. Thesequence of application of the force by a monofilament may berandomized. Patient responses may be recorded, such that a report ordepiction of the data, such as a threshold sensation map visuallyshowing the results of the assessment, may be provided.

In describing the embodiments depicted herein, the device will bedescribed as securing a patient's foot for the purpose of testing theplantar surface of the foot (that is, the underside of the foot thatcontacts the ground). This is because the plantar surface of the foot isa common surface region for developing neuropathy. However, the devicemay be adapted to secure and test any primary body part or limb of apatient, such as a leg, thigh, arm, or hand to evaluate neuropathicconditions. The primary adaptation needed to make such a device usablewith body parts other than a foot is with respect to the clamp apparatusfor securing the tested body part (as described with respect to the footclamp apparatus A below). The remaining assemblies and elements of thedevice would need only minimal changes if at all. Therefore, while theembodiments will be described herein with reference to the foot as theparticular body part being secured, and the plantar surface of the footas the particular body part being tested, it should be understood thatsuch embodiments may be adapted for testing any desired surface regionof the body.

The device is also described as using “noninvasive” testing.“Noninvasive” testing means that the device acts only on the surface ofthe skin and does not prick, puncture, cut, or otherwise become insertedinto the skin.

The device may also be described as “semiautomatic.” This means thatonce set in operation, the device moves automatically to perform one ormore sequences of movement or functions, e.g., to move the head assemblyto a given location and to drive the monofilament attached thereto, asdescribed further herein. These sequences are punctuated by pausesduring which an operator may provide computer instructions or awaitresponse from the patient. For example, once the monofilament is drivento provide a given force against the tested location of the skin surfaceas described herein, the device may pause and await a response by thepatient as to whether the force was sensed against the skin. The devicemay then perform the next sequence of movement or functions once aresponse or instruction has been provided.

As used in this disclosure and the claims, the word “about” when used inreference to a distance means within 10% plus or minus the stateddistance. The word “about” when used in reference to a force means thestated force and a unilateral tolerance of 0.5 gF above the statedforce. For example, if the stated force is 2.0 gF, then the machine willapply the monofilament until it reaches at least 2.0 gF, but not toexceed 2.5 gF.

A computer may be a uniprocessor or multiprocessor machine. Accordingly,a computer may include one or more processors and, thus, theaforementioned computer system may also include one or more processors.Examples of processors include sequential state machines,microprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), gated logic, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure.

Additionally, the computer may include one or more memories.Accordingly, the aforementioned computer systems may include one or morememories. A memory may include a memory storage device or an addressablestorage medium which may include, by way of example, random accessmemory (RAM), static random access memory (SRAM), dynamic random accessmemory (DRAM), electronically erasable programmable read-only memory(EEPROM), programmable read-only memory (PROM), erasable programmableread-only memory (EPROM), hard disks, floppy disks, laser disk players,digital video disks, compact disks, video tapes, audio tapes, magneticrecording tracks, magnetic tunnel junction (MTJ) memory, optical memorystorage, quantum mechanical storage, electronic networks, and/or otherdevices or technologies used to store electronic content such asprograms and data.

In particular, the one or more memories may store computer executableinstructions that, when executed by the one or more processors, causethe one or more processors to implement the procedures and techniquesdescribed herein. The one or more processors may be operably associatedwith the one or more memories so that the computer executableinstructions can be provided to the one or more processors forexecution. For example, the one or more processors may be operablyassociated to the one or more memories through one or more buses.Furthermore, the computer may possess or may be operably associated withinput devices (e.g., a keyboard, a keypad, controller, a mouse, amicrophone, a touch screen, a sensor) and output devices such as (e.g.,a computer screen, printer, or a speaker).

The computer may execute an appropriate operating system such as LINUX®,UNIX®, MICROSOFT® WINDOWS®, APPLE® MACOS®, IBM® OS/2®, ANDROID®, andPALM® OS, and/or the like. The computer may advantageously be equippedwith a network communication device such as a network interface card, amodem, or other network connection device suitable for connecting to oneor more networks.’

A computer may advantageously contain control logic, or program logic,or other substrate configuration representing data and instructions,which cause the computer to operate in a specific and predefined manneras, described herein. In particular, the computer programs, whenexecuted, enable a control processor to perform and/or cause theperformance of features of the present disclosure. The control logic mayadvantageously be implemented as one or more modules. The modules mayadvantageously be configured to reside on the computer memory andexecute on the one or more processors. The modules include, but are notlimited to, software or hardware components that perform certain tasks.Thus, a module may include, by way of example, components, such as,software components, processes, functions, subroutines, procedures,attributes, class components, task components, object-oriented softwarecomponents, segments of program code, drivers, firmware, micro-code,circuitry, data, and the like.

The control logic conventionally includes the manipulation of digitalbits by the processor and the maintenance of these bits within memorystorage devices resident in one or more of the memory storage devices.Such memory storage devices may impose a physical organization upon thecollection of stored data bits, which are generally stored by specificelectrical or magnetic storage cells.

The control logic generally performs a sequence of computer-executedsteps. These steps generally require manipulations of physicalquantities. Usually, although not necessarily, these quantities take theform of electrical, magnetic, or optical signals capable of beingstored, transferred, combined, compared, or otherwise manipulated. It isconventional for those skilled in the art to refer to these signals asbits, values, elements, symbols, characters, text, terms, numbers,files, or the like. It should be kept in mind, however, that these andsome other terms should be associated with appropriate physicalquantities for computer operations, and that these terms are merelyconventional labels applied to physical quantities that exist within andduring operation of the computer based on designed relationships betweenthese physical quantities and the symbolic values they represent.

It should be understood that manipulations within the computer are oftenreferred to in terms of adding, comparing, moving, searching, or thelike, which are often associated with manual operations performed by ahuman operator. It is to be understood that no involvement of the humanoperator may be necessary, or even desirable. The operations describedherein are machine operations performed in conjunction with the humanoperator or user that interacts with the computer or computers.

It should also be understood that the programs, modules, processes,methods, and the like, described herein are but an exemplaryimplementation and are not related, or limited, to any particularcomputer, apparatus, or computer language. Rather, various types ofgeneral-purpose computing machines or devices may be used with programsconstructed in accordance with some of the teachings described herein.In some embodiments, very specific computing machines, with specificfunctionality, may be required. Similarly, it may prove advantageous toconstruct a specialized apparatus to perform the method steps describedherein by way of dedicated computer systems with hard-wired logic orprograms stored in nonvolatile memory, such as, by way of example,read-only memory (ROM).

In some embodiments, features of the computer systems can be implementedprimarily in hardware using, for example, hardware components such asapplication specific integrated circuits (ASICs) or field-programmablegated arrays (FPGAs). Implementation of the hardware circuitry will beapparent to persons skilled in the relevant art(s). In yet anotherembodiment, features of the computer systems can be implemented using acombination of both general-purpose hardware and software.

The Machine and its Operation

FIG. 1 depicts an exemplary embodiment of the neuropathy assessmentmachine shown in an upright, perspective view. The machine has a footclamp apparatus A, a chassis B, a linear motion translation assembly C,and a camera assembly D. Each of these are described further in moredetail and with reference to additional figures.

The chassis B provides a support structure for the moving or operationalelements of the machine. The chassis B may be formed of one or moresolid structures to which the operational elements of the machine areattached. The chassis B may take any form or shape desirable. In theembodiment of FIG. 1 , the chassis is formed of several support bars 4that are joined together to form a rectangular prism, such as by bolts,welding, or any other means of securely joining the support bars 4. Thechassis formed of the support bars 4 is shown isolated from otherelements in FIG. 2 . In FIG. 1 , the chassis is covered on thefoot-facing side by a cover plate 5. The cover plate 5 may be made ofany safe solid material. The cover plate 5 may also have gradients orposition markers located on the face of the over plate 5 to aid theoperator with positioning or relocating the foot within the device. Thechassis B may also be covered with exterior cover plates to hide theinterior workings of the device from the patient's view or otherwiseprovide an aesthetically pleasing design.

Also as depicted in FIG. 1 , the chassis B may have a large steppermotor 31 a attached to a support bar 4 for moving the linear motiontranslation assembly C in a first linear direction. A second largestepper motor 31 b is also shown in the opposite corner for moving thelinear motion translation assembly C in a second linear direction. Asshown on the exemplary embodiment of FIG. 1 , the large stepper motors31 provide motion along perpendicular directions. The large steppermotor 31 is used in connection with the linear motion translationassembly C described further below. In the embodiment of FIG. 1 thelarge stepper motors 31 are each housed within a motor cover 1. A fan 3may also be provided to ventilate and cool each large stepper motor 31.The large stepper motors 31 may be attached as shown in FIG. 1 to asupport bar 4, or they may be attached to the linear motion translationassembly C without being attached to the chassis B.

FIG. 2 shows a camera assembly D attached to a support bar 4 passingacross the middle of one of the large sides of the rectangular prismformed by the chassis B. FIG. 3 depicts the camera assembly D of thisembodiment in greater detail. A camera mounting plate 7 is attached to acentral location on one of the large sides of the chassis B. The cameramounting plate 7 extends perpendicularly outward from the chassis B. Thecamera mounting plate 7 supports a camera mount 8, to which is attacheda camera 9. The camera 9 is directed back towards the chassis B. Thecamera 9 is used to take a picture of the plantar surface of thepatient's foot as described further below. As depicted in the embodimentof FIG. 1 , the camera assembly D is mounted onto the chassis B, whichprovides the benefit of having a single integrated machine for transportand use. However, the camera assembly D, and in particular the camera 9,may be attached to the chassis B from any desirable surface.Alternatively, the camera 9 may be separated from the chassis B. Forexample, the camera 9 may be completely independent from the chassis Band moved into and out of place as desired by the machine operator.Accordingly, it is not necessary for the operation of the machine forthe camera assembly D to be directly attached to the chassis B asdepicted with respect to the exemplary embodiment of FIG. 1 . The cameramount 8 may be adjustable along the camera mounting plate 7 toaccommodate the size and shape of the camera 9. This allows for placingthe camera 9 at the optimal location. The camera 9 takes a photograph ofthe plantar surface of the patient's foot when placed in the device.Such a photograph may be used to select and record testing locations.Furthermore, a report may be generated at the end of the evaluation byplotting the data on the photograph.

The foot clamp apparatus A secures the foot of the tested patient to themachine. The various clamps and structures of the foot clamp apparatus Aare secured to the chassis B. The purpose of the foot clamp apparatus Ais to secure and immobilize the patient's foot during the neuropathyassessment. The foot clamp apparatus A may have one or more supports andclamps directed to securing one or more of the patient's lower calf,ankle, heel, metatarsals, or toes. For example, while the methods ofassessment described herein are directed to testing for neuropathyacross the entire plantar surface of the foot, the machine may bedesigned to test only the plantar surface of the heel, or onlymetatarsals, or only the toes, or some combination thereof. If orexample only the heel and metatarsals are tested, the toes may not needto be secured.

Using the embodiment as depicted in FIG. 1 , the patient may be lyingdown, such that the patient's heel is resting on a support and the footextends upward. The machine is arranged upright to be secured to thefoot. The plantar surface of the patient's foot rests against the footplate 21. The foot plate 21 is preferably transparent and has a grid ofholes. These holes are used for pinpointing the location of applicationof the monofilament for use with various foot sizes.

To immobilize the foot and prevent ankle rotation, a clamping structureis provided. FIG. 4 shows an isolated view of the foot clampingapparatus A from the exemplary embodiment of FIG. 1 . The patient'sankle rests in the ankle support 10. The ankle support is a supportplate for holding up the patient's foot during the testing. The anklesupport 10 is shown in position here to support the ankle, which is themost ergonomically comfortable and stable part of the patient's leg tobe supported. However, the support 10 may also support one or more ofthe patient's lower calf, ankle, and/or heel. A strap secures andstabilizes the ankle as supported by the ankle support 10. As shown inFIG. 1 , the strap may be connected to two strap plates 11, one on eachside of the ankle support 10, in order to strap the ankle (or other partof the leg or foot) to the support 10. Preferably, a minimal amount ofcompression is applied to the ankle by the strap so that the patientdoes not lose blood flow or pressure sensitivity in the foot duringtesting.

The clamping structure as shown in the embodiment of FIGS. 1 and 4 has aclamp base 12 and a foot clamp 13. The machine may have one or moreclamping structures. The embodiment depicted in FIG. 1 has two clampingstructures. The clamp bases 12 are connected to each other by a shaft 23a. A foot clamp 13 houses a sleeve bearing 15 such that the foot clampis capable of moving linearly along the shaft 23 that connects bothclamp bases 12. In this embodiment there are two foot clamps 13. Eachfoot clamp 13 houses a shaft 23 b which interconnects to the clamp base12 closest to it. The foot clamp 13 and shaft 23 b may be locked inplace with a clamp lock 16 attached to the clamp base 12. A lock cover17 applies compression to the clamp lock 16 in order to hold in theclamp base 12. The foot clamp 13 may also have a locator or positioningguide 14 for positioning the foot in the clamping apparatus.

The patient's toes may also be immobilized or pressed against the footplate 21. In the embodiment of FIG. 1 the patient's toes are compressedby one or more toe clamps 19. Each toe clamp 19 has a foot strap guide20. A strap is inserted into the foot strap guide 20 and wrapped aroundor applied against one or more toes to compress the toes against thefoot plate 21.

The clamp bases 12 and the toe clamps 19 are secured to the chassis B ina manner that permits the clamp bases 12 and toe clamps 19 that may beunsecured such that the clamps may be adjusted to accommodate differentsizes of feet. In the embodiment of FIG. 1 each clamp base 12 and toeclamp 19 are secured to a support bar 4 with lock handles 18. The lockhandles 18 may be tightened to secure the clamps to the support 4, orthe lock handles may be loosened to adjust the respective clamps to movelinearly along the support 4. This allows the clamps to be individuallyadjusted to provide proper pressure and fit for immobilizing thepatient's foot.

FIG. 4 is a close up of the foot clamp apparatus A. Its overall shape ismade up of four supports 4. Connected to the supports 4 is the footplate 21, which houses an array of holes in order to accommodate fordifferent foot sizes. The foot plate 21 is further reinforced by twofoot plate support brackets 22, which apply compression to this part andconnect to the supports 4. Likewise, this figure also highlights theclamping features of the machine. The ankle support 10 and the anklestrap plates 11 are used to fix the ankle in place during testing. Theclamp bases 12, foot clamps 13, and locators 14 are assembled togetherwith shafts 23 and large sleeve bearings 15. When these parts arecombined, they create a structure used to keep the foot from rotating byapplying minimal compression. This is achieved by using the clamp locks16 and the lock covers 17. The toes are compressed by an assembly of toeclamps 19 and the foot plate guide 20. The toe clamps 19 and the clampsbases 12 translate linearly along the support 4 and lock in place withthe use of lock handles 18. All of these features allowing for varyingfoot sizes to be tested and also allow for the foot to be reasonablerelocated to for future evaluations.

While the embodiment depicted in FIG. 4 shows the foot clamp immovablysecured to the chassis B, in other embodiments the foot clamp A may bepivotable with respect to the chassis B such that the foot clamp can bepivoted upward and away from the foot plate 21, thereby creating an openarea for unimpeded access for a patient to place a foot on the testplate 21. Once in place, the foot clamp A may be pivoted back down ontothe patient's foot to secure the foot for testing. This may beespecially desirable for patients with limited mobility

The linear motion translation assembly C provides a support andtranslation apparatus for applying the monofilament 44 for neuropathytesting at the desired location on the patient's foot. The lineartranslation assembly C is shown in FIG. 1 as a part of the exemplaryembodiment depicted therein, and in isolation in FIGS. 5 and 6 . Thehead E, which is a particular subassembly of the linear motiontranslation assembly C, is further depicted in FIGS. 7, 8A, and 8B.

The linear motion translation assembly C is secured to the chassis B bythe chassis support plates 6. The chassis support plates 6 may provideadditional rigidity to the chassis B. The various components of thelinear motion translation assembly C may also be secured to the chassissupport plates 6. Bearings 24 are fastened to the chassis support plates6. First rotary shafts 23 c pass through the bearings 24, which permitthe shafts to rotate when driven by the large stepper motors 31 a and 31b. The rotary shaft 23 c driven by large stepper motor 31 a is locatedalong a first side of the chassis B, and the rotary shaft 23 c driven bylarge stepper motor 31 b is located along a second side of the chassisB, which is perpendicular to the first side referenced above in thissentence. The rotary shafts 23 c are connected to the large steppermotors 31 a and 31 b by motor couplings 32. In order to turn the rotarymotion of the large stepper motors 31 a and 31 b into linear motion, asecond rotary shaft 23 d is placed parallel to each first rotary shaft23 c and on the opposite side of the chassis B of its paired firstrotary shaft 23 c. The shafts 23 c and 23 d in each pair are connectedto each other by pulleys 27 and belts 28. In addition, each rotary shaft23 c and 23 d has an X/Y axis connector 29 encompassing the body of theshaft with the shaft passing through head sleeve bearings 25, such thatthe shaft is free to rotate through the X/Y axis connector 29. Each pairof X/Y axis connectors 29 opposite each other are connected by anon-rotating bar 29 b. The two non-rotating bars 29 b pass throughbearings attached to the head E. The belts 28 are secured to the X/Yaxis connectors 29 via the belt tension plates 30. The result is thatwhen one or both of the large stepper motors 31 a and 31 b are drivingtheir respective rotary shafts 23 c, the head E moves proportionally inthe X/Y plane in the space over the foot plate 21. In this manner, thehead E may be moved to a plethora of desired testing locations on thefoot plate 21. Hard stops 26 may be secured near each end of each rotaryshaft 23 c and 23 d to limit the range of motion of the head E. FIG. 6depicts the linear translation assembly in a vertical planar view.

While the present embodiment depicts the linear translation assemblyusing belts and pulleys, other methods of automating motion across anX/Y plane may also be used. For example, in some embodiments, leadscrews may be used. In other embodiments, guide rails and carriages maybe used to stabilize the motion.

FIG. 7 depicts a close-up view of the head E. A head connector 36 hassleeve bearings 25, through which pass the bars 29 b connecting the X/Yaxis connectors 29. The remaining components of the head E are securedto the head connector 36. A head chassis 37 fastens to the headconnector 36 and houses a small stepper motor 38. The small steppermotor 38 is attached to a lead screw 38 b which converts rotationmovement to linear movement. A slider 40 is driven by the small steppermotor 38. Attached to the slider 40 is a load cell connector 45. Amonofilament support connector 39, a monofilament support holder 46 andmonofilament support plate 47 are used to fasten the load cell connectorplate 45 to the slider 40 and the rail 49. This allows for smooth linearmotion of the monofilament when it is being inserted noninvasively intothe plantar surface of the patient's foot. The load cell 41 uses aWheatstone bridge as further described below to convert a change inelectrical resistance arising from the force applied by the monofilamentto the foot to a corresponding change in force. The load cell 41 issecured to the load cell connector plate 45 with standoffs 42. Themonofilament 44 is inserted into the monofilament load cell adapter 43,which is also attached to the load cell 41 with additional standoffs 42.FIGS. 8A and 8B provide additional depictions of the head E.

In other embodiments using a belt-and-pulley system or lead screws,other types of motors may also be used, such as a DC motor. DC motorsmay also be used for the large stepper motors as well.

FIG. 9A shows a front profile view of the machine of the embodiment ofFIG. 1 . FIG. 9B shows a section view of the machine taken along lineA-A in FIG. 9A. The supports 4 form a rectangular prism that houses andprotects the linear motion translation assembly C. The motor cover 1 andthe fan 3 are positioned in proximity of the large stepper motor 31 a,which is housed in the motor cover 1 and ventilated by a fan 3. Thelarge stepper motor 31 a is connected to the shaft 23 c with the motorcoupling 32. The large stepper motor 31 a is also affixed to a supportbar 4 by a motor mount 33. The rotary shaft 23 b drives the pulleys 27and belts 28 wrapped around the pulleys 27.

The chassis support plates 6 provide rigidity and fastening points forthe linear motion translation assembly C. The camera mounting plate 7,camera mount 8, and the camera 9 are all present in this view andconnect to a support bar 4. The cover plate 5 attaches to a support bar4 opposite from the camera 9. The foot plate 21, with the use of thefoot plate support bracket 22, is also affixed to a support bar 4. Theankle support 10 and the ankle strap plate 11 are attached to a supportbar 4 or to the cover plate 5 and are used to fix the ankle in place.The clamp base 12, foot clamp 13, and the locator 14 similarly areattached to a support bar 4 or the cover plate 5 and prevent the footfrom rotating during evaluation. The toe clamp 19 and the foot strapguide 20 similarly are attached to a support bar 4 or the cover plate 5and prevent toe movement during evaluation. These components are able totranslate, can be adjusted for different foot sizes, and can lock inplace with the use of lock handles 18.

FIG. 9B further depicts limit switch mounts 34 and limit switches 35.The limit switches 35 may be used in association with a homing sequencerun upon machine start up. This homing sequence may be used to positionthe machine accurately and is preferably run prior to each newevaluation (an evaluation being one or a series of tests on a foot). Thelimit switches 35 provide an electronic limit to the X/Y motion of thehead E based on the linear motion translation assembly C and the motorand pulley systems included therein. Hard stops 26 may be installed asphysical limits in combination with or as alternatives to the limitswitches 35. Hard stops 26 may also be provided as a physical safetybarrier in the event a limit switch 35 fails.

FIG. 10 shows a plan view detail of head E and the foot plate 21. Asdescribed above, the foot plate 21 has numerous small holes. These holesare preferably arranged in an X/Y grid. Once the head E is directed to aspecific grid location as described further below, the monofilament 44is driven through the hole at that location to be noninvasively insertedinto the patient's foot. The monofilament 44 is driven by the smallstepper motor 38. The small stepper motor 38 is secured to the headchassis 37. Again, a DC motor or other type of motor may be used inother embodiments. The slider 40 converts the rotational movement of thesmall stepper motor 38 lead screw into linear translation. The slider 40also connects to the load cell connector plate 45 to provide a stableplatform for securing the load cell 41 with the use of standoffs 42. Theload cell 41 is then attached to the monofilament load cell adapter 43,with standoffs 42, which houses the monofilament 44. Additionally, thehead connector 36 utilizes sleeve bearings 25 which glide through shaft23. This shaft 23 is secured to the X/Y axis connector 29 which also hasa sleeve bearing 25 guided through an additional shaft 23.

In addition to the diagnostic tool, another device is used to receivethe patient's responses to the insertion of the monofilament. Forexample, the patient may verbally inform the operator of a sensation ofthe monofilament when it was applied, and this may be recorded andstored in a computer as described further below. Alternatively, thepatient may respond using an electronic counter device such as thatshown in FIG. 11 . A handheld counter 50, which is used to collect thepatient's response during evaluation. The counter 50 houses a LEDpushbutton 52. If the patient experiences the sensation of themonofilament 44 when it is inserted into the foot, the patient depressesthe button. In some embodiments the LED may blink a preset period oftime (e.g., 5 seconds) during the time when the monofilament 44 is beingapplied so that the patient knows when to focus on the insertion of themonofilament 44 for any sensation. The counter 50 may be ergonomicallydesigned and hand neutral. It can also be held in multiple ways toaccommodate the patient's needs. Other methods of receiving thepatient's response may also be used.

FIG. 12A shows a plan view of the counter 50 with a section line C-C,and FIG. 12B shows a section view of the counter 50 along the sectionline C-C. of the handle 50. The LED pushbutton 52 is held within thecounter 50. A cap 51 is provided on the underside to enclose and hidethe counter electronics stored within.

The electronic components for operating the machine may be maintained ina box, cabinet, or other container separated from the machine, or theymay be integrated onto the machine, such as being attached to a supportbar 4. FIG. 13 depicts a wiring diagram of the electronic components forthe embodiment of FIG. 1 of the machine. A power supply 53 suppliespower for the large stepper motor drivers 55. The power supply 53 isalso connected directly to a buck converter 54 which is then used topower the stepper motor driver 56. Alternatively a secondary powersupply could be adopted in other embodiments, instead of the buckconverter 54. A computer 57 is provided having a processor, a hard drivefor storing instructions for operating the device and for storingoutputs such as images from the camera 9, user responses from thecounter 50, and related load cell data. The computer may also have adisplay. The computer is connected to microcomputer A 58 andmicrocomputer B 59. Microcomputer A 58 is used to control the largestepper motor drivers 55. These drivers hook up to the large steppermotors 31 a and 31 b used for linear translation. Furthermore, themicrocomputer A 58 hooks up to the limit switches 35, which are used forthe homing sequence and for additional safety features. Microcomputer B59 directly connects to the stepper motor driver 56 which hooks up tothe small stepper motor 38. Small stepper motor 38 assists in insertingthe monofilament 44 noninvasively into the foot. Lastly microcomputer B59 is linked to the counter 50, which houses the LED pushbutton 52. Thisis used to gather the patient's response following administration of apressure stimulus. Other wiring designs and component parts may be usedto achieve the functions described with respect to the exemplaryembodiment.

General Method of Using the Machine for Evaluating Neuropathy in aPatient

Neuropathy symptoms present on a patient's foot may be evaluated using amachine as disclosed herein. The machine moves a monofilament in 3Dspace in order to apply a pressure stimulus on the plantar surface ofthe foot. This translation is achieved with the use of stepper motorswhich when paired with belts and pulleys allow the monofilament to bepositioned anywhere within the constraints of the machine.

A patient's foot is secured in the foot clamp apparatus A with theplantar surface of the foot resting against the foot plate 21. The footplate 21 has a plurality of holes preferably arranged in a grid pattern,through which the monofilament 44 is applied to the foot of the patient.Therefore, each hole in the foot plate 21 corresponds to a potentialtesting location. These testing locations can be designated by theoperator using the computer 57.

Once the patient's foot is secured, the camera 9 takes a digitalphotograph of the plantar surface of the foot, which is partiallyvisible through the holes in the foot plate 21. An exemplary image isprovided as FIG. 14 showing a patient's foot behind the foot plate 21but visible through the holes. Using this image as displayed by thecomputer 57, the operator can select points or regions of the foot fortesting by selecting the specific hole locations on the photograph.

The large stepper motors 31 a and 31 b are calibrated to rotate througha series of uniform, discrete turns or steps such that each discretestep advances the head E to the next hole over in the grid. In this way,the stepper motors 31 a and 31 b drive the head to the locationidentified by the operator on the computer 57. Once situated over theproper hole location, the small stepper motor 38 attached to a leadscrew is used to drive the monofilament, noninvasively, until itcontacts the patient's foot at a prescribed force, as described furtherherein. The load cell measures the force at which the monofilament isapplied. The microcomputer B or the computer provides instructions todrive the monofilament to a prescribed force as measured by the loadcell, at which time the small stepper motor 38 stops. In this manner,the machine can be set to apply a desired gram-force amount of force andthen retract the monofilament. The machine may be designed to producebetween, e.g., 0.2-30 gF using an appropriately rated monofilament. Thepreferred monofilament for use with the machine is rated to buckle at 10gF, as the inability to sense a monofilament applied at 10 gF is amedical indicator of loss of protective sensation in the foot. However,different monofilaments, with different lengths, cross sectional areas,and materials can be used to alter this range. To ensure an accuratelyapplied force, the load cell reads at a fast rate and the computer isprogrammed to slow the insertion of the monofilament until the forceapplied reaches the desired value. In describing the usage and testingmethods below, the testing will be described with respect to a 10 gFmonofilament, but it is to be understood that a machine designer oroperator could design the machine and testing for a monofilament thathas a buckling limit higher or lower than 10 gF without departing fromthe scope of this disclosure.

When the monofilament is applied to the foot at the desired force, thepatient is then prompted to respond with whether they felt the appliedforce of the monofilament. This may be a verbal request, or the patientmay be prompted such as by the LED pushbutton 52 in the counter 50described with respect to the exemplary embodiment.

The patient's response and the recorded force at the load cell are thenrecorded for the given location. Additional testing at a given locationor at other locations on the foot may follow, as described furtherherein.

Once a patient's threshold of sensation is taken for one or morelocations, a sensitivity map, such as that depicted in FIG. 15 may beprepared. Using the image taken of the patient's foot, the magnitude ofsensed threshold force can be plotted at each location. This sensitivitymap can be used for evaluation and long-term tracking of changes insensation because it is tied to an image of the actual foot, not anabstract chart or representation. This map can be examined by both thepatient and the physician. It also provides a quantitative analysis ofthe degree of neuropathy present and can be used to monitor changes aspart of potential treatments.

Testing Protocols

In addition to the structure of the machine and its general methods ofuse, the inventors also identified testing protocols for evaluatingneuropathy on a patient's foot.

Once the patient places their foot in the machine the computer codeprovides for taking an image of the patient's foot through thetransparent foot plate 21. The image is displayed to the operator. Theoperator selects locations to be assessed on the foot in order todetermine the threshold sensitivity at each testing location. In sometesting protocols, the operator selects multiple locations on the foot,including at least one location on a distal phalange, at least onelocation on a metatarsal head, and at least one location on the heel. Incertain protocols, 13 locations may be selected. These locations mayinclude 5 locations on the distal phalanges, 5 locations on themetatarsal heads, and 3 locations on the heel. Once selected, thecomputer code provides for converting the selected locations from thepixels on the computer display to inches, centimeters, or any otherdesired unit of measurement. The locations may be rounded to the nearestquarter inch, or such other distances as the holes on the foot plate 21are separated.

Where locations are selected for multiple regions, the 3 regions will beevaluated one at a time in a specific testing order. The inventorsidentified four unique testing order paths (Table 1) to test locationsin those regions. The selected testing order paths represent the mosttime efficient order in which the regions are evaluated, based on therelative distance between one another. Other testing order paths, whichare not necessarily time efficient, can also be used for assessment.

TABLE 1 Machine Testing Order Paths Testing Order Paths 1 2 3 4 1^(st)Heel Distal Metatarsal Heel Phalanges Heads 2^(nd) Metatarsal MetatarsalDistal Distal Heads Heads Phalanges Phalanges 3^(rd) Distal Heel HeelMetatarsal Phalanges Heads

Furthermore, within each region, the computer program may generate arandom testing order for all of the locations within each of the 3regions so as the patient will not able to predict the order in whichlocations are accessed. This results in neither the patient nor theoperator knowing the testing order, removing any bias from assessment.

The monofilament is then moved into location by the machine and thecomputer instructs the machine to apply the monofilament at specificloads. The patient will be instructed to press the button 52 if theyfelt the monofilament and to not push the button if they did not feelit. The patient is given a discrete time, e.g., five seconds, to respondif the patient senses the monofilament pressure. For example, where thecounter 50 described above is used, the LED may flash to signal to theuser to focus on whether any pressure is being sensed and to click thebutton 52 if the patient does feel the monofilament. This process isrepeated for multiple pressures until the minimum threshold value isdetermined at the specific location. In some cases the protocol mayapply the monofilament at increasing magnitudes of force (0.2, 0.7, 2.0,4.0, 6.0, 8.0, and 10.0 gF) until the patient can sense themonofilament. Alternatively, the forces may be applied in decreasinglevels of magnitude. Applying the monofilament in increasing magnitudesof force would be better suited for a healthy patient, while applyingthe monofilament in decreasing magnitudes of force would be bettersuited to individuals who are suspected of already having a loss ofprotective sensation.

In addition to these methods, the inventors also determined that a“homing in” sequence could identify the least amount of sensationperceived by a patient using the least number of applications possible,especially if the patient is in the middle of the threshold sensitivityspectrum or if the patient's sensitivity is unknown. A flowchart of thisforce testing protocol is provided at FIG. 16 . The patient first isasked to respond with a 0.2 gF load applied. If the patient can feel themonofilament, the computer directs the machine to move the monofilamentto the next selected testing location. If the patient cannot feel the0.2 gF then a 10.0 gF is applied. If the patient cannot feel the 10.0 gFthen the assessment at this location ends, since they are incapable ofsensing the greatest amount of force tested using a 10 gF monofilament.If the patient can feel 10.0 gF, then this will start an iterativeprocess to find what value of force between 0.2 gF and 10.0 gF thepatient can sense, according to the flowchart shown in FIG. 16 .

In addition, the computer may be programmed to include testing for“false positives” to assess whether the patient is giving inaccurateanswers. A false positive will either occur before or after thethreshold sensitivity is determined per location. A false positive willprompt the monofilament to move forward but will not contact theindividual's skin. This action mimics the sound of an actual applicationof the monofilament. At the conclusion of a false positive test the LEDpushbutton will light up and blink to ask the patient if a force wasfelt, despite a force not being applied. Alternatively, the patient maybe verbally asked whether any sensation was felt if a counter 50 withpushbutton 52 is not provided.

In this methodology a patient with a high degree of sensation lossshould complete the assessment in the same amount of time it would takea healthy individual. A patient in the middle between these twospectrums will take more time to complete the assessment, but their timewill still be improved by limiting the amount of times the monofilamentis applied. Preliminary testing showed that it takes between 7-12minutes per foot with the above parameters.

It is to be understood that any given elements of the disclosedembodiments of the invention may be embodied in a single structure, asingle step, a single substance, or the like. Similarly, a given elementof the disclosed embodiment may be embodied in multiple structures,steps, substances, or the like.

The foregoing description illustrates and describes the processes,machines, manufactures, compositions of matter, and other teachings ofthe present disclosure. Additionally, the disclosure shows and describesonly certain embodiments of the processes, machines, manufactures,compositions of matter, and other teachings disclosed, but, as mentionedabove, it is to be understood that the teachings of the presentdisclosure are capable of use in various other combinations,modifications, and environments and are capable of changes ormodifications within the scope of the teachings as expressed herein,commensurate with the skill and/or knowledge of a person having ordinaryskill in the relevant art. The embodiments described hereinabove arefurther intended to explain certain best modes known of practicing theprocesses, machines, manufactures, compositions of matter, and otherteachings of the present disclosure and to enable others skilled in theart to utilize the teachings of the present disclosure in such, orother, embodiments and with the various modifications required by theparticular applications or uses. Accordingly, the processes, machines,manufactures, compositions of matter, and other teachings of the presentdisclosure are not intended to limit the exact embodiments and examplesdisclosed herein. Any section headings herein are provided only forconsistency with the suggestions of 37 C.F.R. § 1.77 or otherwise toprovide organizational queues. These headings shall not limit orcharacterize the invention(s) set forth herein.

We claim:
 1. A machine for evaluating the presence of neuropathy in apatient, comprising: a testing plate having a first side and a secondside and comprising a plurality of holes, and configured to have thepatient's skin stabilized against the first side; a camera operable totake a photograph of the patient's skin visible through the holes fromthe second side of the testing plate; a head assembly translatablewithin a plane parallel to the second side of the testing plate anddisposed in between the camera and the testing plate, the head assemblycomprising a retractable monofilament; and a computer programmed toreceive input for selecting a testing location on the patient's skinwherein the testing location is correlated with one of the plurality ofholes in the testing plate, position the head assembly over the testinglocation, and apply the monofilament to the patient's skin at thetesting location and at a specified force.
 2. The machine of claim 1,further comprising a linear translation assembly mounted to the chassisand having first and second translation motors and a drive trainconnected to the head assembly, such that the translation motors causethe head assembly to be movable in an X/Y-plane parallel to the secondside of the testing plate.
 3. The machine of claim 1 wherein operationcan be semi-automatic.
 4. The machine of claim 1 wherein the forceapplied ranges from about 0.2 to about 30 gF.
 5. The machine of claim 1wherein the same monofilament can be used to apply different forces. 6.The machine of claim 1 wherein the testing plate is transparent.
 7. Themachine of claim 1 wherein the computer is programmed to receive theimage and to receive input for selecting a testing location bydesignating a location on the image.
 8. The machine of claim 7 whereinthe computer is further programmed to provide an output comprising animage of the patient's skin with the force testing information appliedat the testing location.
 9. The machine of claim 8 wherein the computeris further programmed to store testing information.
 10. The machine ofclaim 1 wherein the patient's skin being tested is the plantar surfaceof a foot of the patient.
 11. The machine of claim 1 further comprisinga clamp for securing the patient's skin to the first side of the testingplate.
 12. A machine for evaluating the presence of neuropathy in apatient, comprising: a testing plate having a first side and a secondside and comprising a plurality of holes, wherein the patient's skin maybe stabilized against the first side of the testing plate; a cameraoperable to take a photograph of the patient's skin visible through theholes from the second side of the testing plate; a head assemblytranslatable within a plane parallel to the second side of the testingplate, the head assembly comprising a retractable monofilament; achassis having a first side to which the testing plate is secured, and asecond side opposite the first side to which the head assembly issecured, wherein the camera is mounted to the chassis and is disposedexternal to the chassis; and a computer programmed to receive input forselecting a testing location on the patient's skin wherein the testinglocation is correlated with one of the plurality of holes in the testingplate, position the head assembly over the testing location, and applythe monofilament to the patient's skin at the testing location and at aspecified force.
 13. The machine of claim 12 wherein operation can besemi-automatic.
 14. The machine of claim 12 wherein the force appliedranges from about 0.2 to about 30 gF.
 15. The machine of claim 12wherein the force applied ranges from about 0.2 to about 10 gF.
 16. Themachine of claim 12 wherein the testing plate is transparent.
 17. Themachine of claim 12 wherein the computer is programmed to receive theimage and to receive input for selecting a testing location bydesignating a location on the image.
 18. The machine of claim 17 whereinthe computer is further programmed to provide an output comprising animage of the patient's skin with the force testing information appliedat the testing location.
 19. The machine of claim 18 wherein thecomputer is further programmed to store testing information.
 20. Themachine of claim 12 wherein the patient's skin being tested is theplantar surface of a foot of the patient.